Dynamo-electric machine component conveying systems and load/unload devices

ABSTRACT

An improved conveying system in a parallel processing production line for dynamo-electric machine components having a magnetic core, the conveying system having a main conveyor extending along all of the processing machines of the production line and a load/unload device for transferring components between the main conveyor and a selected processing machine. Components to be processed are loaded directly from the main conveyor onto the load/unload device without the use of an intermediate conveyor. The load/unload device has a base platform with an alignment area at which transfer between the load/unload device and either the main conveyor or a selected processing machine occurs. Two component holders (e.g., collets) are movably mounted on the base platform for alternate positioning at the alignment area. The load/unload device alternately positions the gripping ends of the component holders adjacent the main conveyor and a selected processing machine. The central axis of the load/unload device remains fixed during movement of the load/unload device.

BACKGROUND OF THE INVENTION

The present invention relates to improving conveying systems fortransporting dynamo-electric machine components between a series ofprocessing machines of an automatic, parallel processing, productionline, and for delivering such components to a selected one of the seriesof processing machines for processing. More particularly, the presentinvention relates to conveying systems for transporting dynamo-electricmachine components (e.g., electric motor parts) having magnetic coresbetween a main conveyor and a selected one of a series of processingmachines working in parallel along the main conveyor. The presentinvention further relates to load/unload devices for transferringdynamo-electric machine components between the main conveyor and theselected processing machines. Dynamo-electric machine components areloaded directly from the main conveyor line onto a load/unload device,and from the load/unload device onto the selected processing machine ina time-efficient manner. The load/unload device has two componentholders (e.g., collets) movably mounted on a base platform for alternatealignment for loading and unloading of dynamo-electric machinecomponents. The load/unload device moves between the main conveyor andthe selected processing machine while the central axis of theload/unload device preferably remains fixed.

Automatic manufacturing lines for processing dynamo-electric machinecomponents having a magnetic core (hereinafter "components") typicallytransport the components between a variety of machines. (By "magneticcore" it is meant that the core is magnetizable, not that it isnecessarily magnetized at all times.) For example, armatures areconveyed to such machines as winding machines and fusing machines. Thepresent invention is specifically related to conveying such componentsas armatures to any type of machinery or processing apparatus thatcharacteristically is used in parallel with at least one other identicalmachine on a particular conveyor section. These machines typically haveslower production rates than machinery that is not used in parallelproduction lines (i.e., machinery in manufacturing lines where only onemachine of a particular type is present on the line). These machinesalso usually require the components to be removed from the pallets onwhich they are conveyed in order to be processed. Once processing hasbeen accomplished, the component is returned to an empty pallet fortransport to other downstream machines of the manufacturing line.

One example of a conveying system is shown in FIG. 1. A main conveyorsection 100 transports pallets carrying components such as armatures toany one of the machines 102, 104, and 106 of the same type. Additionalconveyors 112, 114, and 116 are placed in front of respective machines102, 104, and 106 for conveying to a selected machine components to beprocessed. Transfer devices 122, 124, and 126 remove pallets carryingcomponents to be processed from main conveyor section 100 and transferthe pallets to the additional conveyors 112, 114, and 116, respectively.

Once a pallet is on one of additional conveyors 112, 114, 116, thecomponent it is carrying can be transferred to a corresponding machine102, 104, 106 for processing. The pallet can then receive a processedcomponent from the machine along which the pallet is conveyed. After thepallet receives a processed component, the pallet can move to thedownstream transfer device 132, 134, 136 associated with the additionalconveyor on which the pallet is conveyed, and be returned to mainconveyor section 100. The pallet, now carrying a processed component(such as a wound armature), is subsequently transferred to furtherconveyor section 110.

The pallets that carry the components for processing are typicallyprovided with coding devices which indicate the processing condition ofthe component being carried. More precisely, these devices indicatewhether a component has or has not been processed by one of machines102, 104, 106. Writing devices may also be used to change the codinginformation so that the device indicates that the component has beenprocessed.

Devices for reading the coding devices are placed before transferdevices 122, 124, and 126 to determine whether a pallet needs to betransferred to an associated machine for processing. If the pallet neednot be transferred (because the component it is carrying has alreadybeen processed), the pallet travels to the end of main conveyor section100 for transfer to further conveyor section 110. Reading of the codingdevice occurs each time a pallet reaches one of transfer devices 122,124, 126. The pallets are stopped against an abutment surface in orderto have their coding devices read while the transporter belts continueto move. Before a pallet is transferred to further section 110, anotherreading of the coding device is performed to determine whether thepallet is carrying an unprocessed component and needs to be returned tothe beginning of main conveyor section 100.

Additional conveyor sections 112, 114, and 116 are provided with devicesfor determining how many pallets are queued up on the selected conveyorwaiting to deliver a component to a corresponding machine 102, 104, 106.If the number of pallets on a particular additional conveyor section isat the maximum, then transfer by the transfer device related to thatparticular section will not transfer a pallet to that section until aplace for another pallet is created. Thus, pallets having componentswhich need to be processed travel down main conveyor section 100 untilthey find a free additional conveyor section 112, 114, 116. If thepallet reaches the end of main conveyor section 100 without having founda free additional conveyor section (e.g., because machines 102, 104, and106 are all occupied), then transfer device 140 transfers the pallet toreturn conveyor 142, and transfer device 144 returns the pallet to thebeginning of main conveyor section 100. The pallet then once againattempts to find a free additional conveyor section 112, 114, 116, asdescribed above.

A possible disadvantage of this type of conveying system in somesituations is the delays that occur while pallets and components aretransferred. When pallets are transferred by transfer devices 122, 124,126, 132, 134, 136 between main conveyor section 100 and additionalconveyor sections 112, 114, 116, pallets upstream of the pallet beingtransferred are halted to allow the transfer to occur. Loading andunloading of components between pallets on additional conveyor sections112, 114, 116 and machines 102, 104, 106 occurs by stopping the palletin front of the associated load/unload device 152, 154, 156, removingthe component to be processed, and placing on the now empty pallet aprocessed component so that the pallet can be transferred back to mainconveyor section 100 without waiting for completion of processing of thecomponent it had delivered.

Another characteristic of systems of the type shown in FIG. 1 is thatthe additional conveyor sections tend to require additional floor spaceand may increase the maintenance requirements of the system. As shown inFIG. 1, five different conveyor sections must continue to run smoothlyfor the conveying system to be fully operational.

Finally, load/unload devices 152, 154, 156 may be regarded as relativelyslow in transferring components between additional conveyor lines 112,114, 116, and machines 102, 104, 106, respectively.

A second type of conveying system is shown in FIG. 2. A main conveyor200 transports pallets carrying components to a number of machines, suchas winder 202, in a parallel processing system. When a pallet carrying acomponent to be processed approaches an available machine, the pallet istransferred to a secondary conveyor 210, which is preferablyperpendicular to main conveyor 200. From secondary conveyor 210, thecomponent to be processed is transferred to a collet on carriage 220.Carriage 220 is positioned on slide 230, which is cantilevered fromsupport 240. Slide 230 slides in direction 232 to bring carriage 220adjacent secondary conveyor 210 in a plane spaced above the plane ofsecondary conveyor 210. As viewed in FIG. 2 the stopping point of slide230 is below the depicted location of the pallet on secondary conveyor210. The component on this pallet is then lifted off the pallet.Carriage 220 slides laterally on slide 230 along direction 222 toalternately align collet 226 with the pallet (to receive a componentfrom the conveying system for processing) and to align collet 224 withthe pallet (to return a processed component to the conveying system).Slide 230 slides along direction 232 to transport carriage 220 to winder202 to load a processed component onto collet 224 (then aligned withwinder 202). Carriage 220 then slides along direction 222 to deliver acomponent to be processed, carried by collet 226, to winder 202. Slide230 then slides back to additional conveyor 210 to repeat the abovesteps.

Because this conveying system also uses additional conveyor lines 210 towhich pallets are transferred, this system may also have theabove-described possible disadvantages of time delays during pallettransfer, the necessity of additional floor space, and increasedmaintenance requirements. The length of travel of slide 230 also tendsto be quite long.

A third type of a conveying system, described in Nussbaumer U.S. Pat.No. 4,718,533, does not use additional conveyor sections (such as thoseshown in FIG. 1). When a pallet needs to be loaded or unloaded at aparticular machine, the pallet is lifted off the main conveyor so thatpallets that need to reach a downstream portion of the conveyor line cantravel beneath the lifting device. This system tends to requirecomplicated pallet-lifting equipment.

In view of the foregoing, it would be desirable to provide a conveyingsystem and method that would quickly and efficiently convey componentsto be processed through a manufacturing line, and transport thecomponents between the means conveying the components and the machinesin the manufacturing line.

It would also be desirable to provide a conveying system and method thatwould not require conveyor lines in addition to the main conveyor lineor complicated pallet lifting equipment that may tend to increasemachinery costs and require large areas of manufacturing plant floorspace.

It would further be desirable to provide a load/unload device and methodthat quickly and efficiently transports components between a conveyorline and a processing machine.

SUMMARY OF THE INVENTION

It is therefore an object of this invention to provide a system andassociated method for quickly and efficiently conveying components to beprocessed through a parallel processing production line, andtransporting the components between the means conveying the componentsand the machines in the production line.

It is also an object of this invention to provide a conveying system andmethod that does not require conveyor lines in addition to the mainconveyor line or complicated pallet lifting equipment that tends toincrease machinery costs and require large areas of manufacturing plantfloor space.

It is a further object of this invention to provide a load/unload deviceand method that quickly and efficiently transports components between aconveyor line and a processing machine.

These and other objects are accomplished in accordance with theprinciples of this invention by providing a system having a mainconveyor for conveying components (defined above to mean dynamo-electricmachine parts having a magnetic core) along a series of machines in aparallel processing system, and a load/unload device adjacent eachmachine for transferring components between the adjacent machine and themain conveyor. The load/unload device is movable between the mainconveyor and the processing machine with which the particularload/unload device is associated. The load/unload device has a baseplatform for carrying a movable carriage on which at least two componentholders such as collets are positioned. The base platform has analignment area at which a component holder is positioned for transfer ofa component. Each time the alignment area is positioned for a transfer,the component holders are sequentially positioned at the alignment areafor delivery of a component from one component holder and receipt ofanother component by another component holder.

The number of pallets present in a particular conveyor section of theconveyor line depends on the upstream supply of the conveyor line andalso on the productivity of the machinery being supplied by a relatedconveyor section. The conveyor has belts that move continuously duringmanufacturing to move the pallets between machines in theconveyor/manufacturing line. The conveyor sections transport thecomponents between machines such as winding machines, fusing machines,or any type of machinery that characteristically has more than onemachine working in parallel on a particular conveyor section.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and advantages of the invention, its nature,and various advantages will be apparent from the following detaileddescription of the preferred embodiments, taken in conjunction with theaccompanying drawings, in which like reference characters represent likeelements throughout, and in which:

FIG. 1 is a schematic plan view of a prior art system using additionalconveyor sections and load/unload devices which transfer componentsbetween pallets and processing machines;

FIG. 2 is a schematic plan view of a prior art system using anadditional conveyor section and a slidable carriage for transferringcomponents between pallets on the conveyor section and processingmachines;

FIG. 3 is a schematic plan view of an illustrative embodiment of theconveying system of the present invention;

FIG. 4a is a graphic representation of the time required to transportcomponents between a prior art conveying system and one of a series ofprocessing machines, compared with FIG. 4b which is a graphicrepresentation of the time required to transport components between theconveying system of the present invention and one of a series ofprocessing machines;

FIG. 5 is an isometric view of an illustrative embodiment of theconveying system and load/unload device of the present invention;

FIG. 6 is a schematic plan view of the conveying system and load/unloaddevice of FIG. 5, showing the load/unload device loading and unloadingcomponents onto and from the main conveyor; and

FIG. 7 is a schematic plan view of the conveying system and load/unloaddevice of FIG. 5, showing the load/unload device loading and unloadingcomponents onto and from a selected machine along the production line.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A conveying system 300 for a parallel processing system/production linein accordance with the principles of the present invention is shownschematically in FIG. 3. System 300 only has one main conveyor 310 fromwhich components to be processed are removed for processing and to whichprocessed components are returned. Main conveyor 310 extends along allof the processing machines in the series of processing machines of theproduction line. It will be understood that main conveyor 310 isreferred to as a single conveyor, but may be several separate, alignedconveyors forming a continuous conveyor line extending along all of theprocessing machines in the series. A return conveyor 312 is present toreturn unprocessed components that could not be processed during theirfirst pass along conveyor 310 (e.g., because all the machines orload/unload devices were occupied when the component passed by) to thebeginning of main conveyor 310 to once again convey the componentsthrough the system. While on conveyors 310 and 312 each component issupported on a pallet 320. Each conveyor 310, 312 preferably has twoparallel conveyor belts, as shown in further detail in FIG. 5, and asdescribed in further detail below. It will be understood that any othermeans for transporting components (or pallets) between the processingmachines in the system may be used.

Conveyor 310 carries the components to load/unload devices 322, 324, and326, which load and unload components to and from processing machines332, 334, and 336, respectively. Main conveyor 310 extends between allof processing machines 332, 334, 336. Load/unload devices 322, 324, and326 can load and unload components in a very short time, as will bedescribed in further detail below. Accordingly, additional conveyorsparallel or perpendicular to main conveyor 310, such as are employed inthe prior art, are not necessary to transport components to therelatively slow processing machines to be used in the present invention.

When a pallet reaches a load/unload device 322, 324, 326, if thecomponent carried thereon needs to be processed, then the pallet ishalted to allow for unloading of the component onto the load/unloaddevice and subsequent loading of the pallet with a processed component.Pallets upstream of the pallet being loaded/unloaded are halted whileloading/unloading occurs. Because the time required to load/unload acomponent is extremely short, the conveying system is capable ofoperating at approximately the same production rate of a parallelprocessing system of the prior art having the same number of processingmachines 332, 334, 336. Preferably the component transfer times in thesystems of this invention are less than those in prior art systems. Buteven if the present transfer times are slightly greater than in priorart systems, the overall production rate and/or average efficiency ofutilization of the production machines may be the same as or greaterthan in prior systems. This will now be explained in more detail.

A comparison of time graphs relating to the operation of the prior artsystem of FIG. 1 (requiring an additional parallel conveyor section) andthe operation of the present system is shown in FIG. 4. In graph (a),time T₁ * is the time required by the prior art system of FIG. 1 for theentire unloading of a component to be processed from the conveyor andsubsequent loading of a processed component onto the conveyor. Time T₁ *causes halting of the pallets and therefore stops supply of the palletsto the machines. This time includes time T_(A) * for halting a palletand reading its coding device, time T_(B) * for transferring a palletfrom the main conveyor section to the additional conveyor section, andtime T_(C) * for transferring a pallet from the additional conveyorsection to the main conveyor section. In contrast, in graph (b), thetime T₁ is the total time required for the load/unload device of thepresent invention to remove a component to be processed from a pallet onthe main conveyor and to load a processed component on the samepallet--achieving the same effect as all the steps of graph (a) in apractically equal if not shorter time. Time T₁ also corresponds to thetime during which pallets are halted and accordingly determines thedelay for the pallets that have been halted to reach successive machinesfor processing. The time delay for halting pallets is a basic parameterfor determining the production capacity of any of the systems that aredescribed herein. That time delay is also a parameter for determiningthe efficiency with which the machines placed in the parallel processingproduction line are used.

A comparison of the production capabilities of the systems of FIGS. 1and 3 begins by noting that the two systems have the same number ofproduction machines (e.g., winders), which means that they aretheoretically capable of producing the same production rates. Inpractice, the machines of each system will only be used for a fractionof their maximum possible production rate. This fraction depends on theconveying system with which the machine is working and is influenced bythe timing of the system to supply pallets to the machines. In thesystem of FIG. 1, this timing depends on the time to unload and to loadthe pallets off and on conveyor 100 and the time to read the code of thepallet at points 122, 124, or 126. In the system of FIG. 3 this timingdepends on the time that a pallet is required to stop at a machine inorder to unload and load components between load/unload device 322, 324,or 326 and the pallet.

The fraction of a machine's maximum production capability that isactually used is often defined as the "efficiency" of use of themachine. A comparison between the systems of FIGS. 1 and 3 shouldinclude an examination of this efficiency fraction for the individualmachines which are present in the systems. For the system of FIG. 1 thisefficiency fraction is very high (e.g., 99%) for the first machine ofthe system (the one on the extreme left), a little lower (e.g., 98%) forthe machine in the middle, and much lower (e.g., 95%) for the machine onthe extreme right. For the system of FIG. 3 the efficiency fractiondescends more gradually from the first machine (on the left) to the lastmachine (on the right) (e.g., 99% for the first machine, 98% for themiddle machine, and 97% for the last machine). These results show thatthe system of FIG. 3 is capable of obtaining high production rates fromthe overall system and a more uniform distribution of efficiency of useamong the machines. This last consideration is a positive aspect becauseit means that all the machines are being used near to their highestcapabilities of producing. Finally, the system of FIG. 3 has animportant advantage over the system of FIG. 1 because it requires lessconveying equipment, occupies less floor space, and can function welleven without coding devices on the pallets.

The times T₁ * and T₁ shown in the graphs of FIG. 4 coincide with thetimes described above for reaching the above-mentioned conclusionregarding the comparison between the system of FIG. 1 and the system ofFIG. 3. In the FIG. 4 graphs the time T₁ * for the system of FIG. 1 isshown as being longer than the time T₁ of the system of FIG. 3. However,the same conclusion regarding comparison between the systems of FIGS. 1and 3 can be reached even if time T₁ * is somewhat shorter than time T₁.The irregularity with which the interruption of pallet supply occurs inthe system of FIG. 1 can result in the system of FIG. 3 being moreproductive and/or having more uniformly distributed production than thesystem of FIG. 1 even if T₁ * is slightly less than T₁.

A conveying system 300 and load/unload device 322 (which issubstantially identical to devices 324 and 326) for use in an armaturewinding production line/parallel processing system in accordance withthis invention are shown in greater detail in FIG. 5. (See also FIGS. 6and 7 which show the load/unload device of FIG. 5 in different positionsand operating conditions.) As shown, a pallet 320 is carried by mainconveyor 310 to load/unload device 322. Main conveyor 310 preferably hastwo parallel belts 510 and 511 which continuously move between machinesin the system. Likewise, return conveyor 312 preferably has two parallelbelts 512 and 513 which continuously move pallets carrying componentsthat need to be processed from the end of main conveyor 310 to thebeginning of main conveyor 310. The two belts 510 and 511 that are usedin main conveyor 310 preferably are spaced apart a sufficient distanceto allow a movable stop 342 to come up between the belts and stop apallet 320 under gripper 530.

A gripping device 530 (such as the gripping device described inSantandrea et al. U.S. Pat. No. 5,257,689 or Andorlini et al. U.S. Pat.No. 5,253,912) descends and then grips, lifts, and removes armature 520from the stopped pallet. Gripping device 530 also rotates 180° about itsvertical axis as it lifts armature 520. This reverses armature 520 endfor end from its position on pallet 320.

When collet 532 of load/unload device 322 is aligned with grippingdevice 530 at an alignment area associated with load/unload device 322(see FIG. 6 for this condition of load/unload device 322, although FIG.6 shows a differently numbered armature 600 prior to the above-mentioned180° rotation of gripping device 530), collet 532 removes armature 520from gripping device 530. Collet 534 should already be gripping a woundarmature it received from winder 500 (unless the conveyor system hasjust begun processing components) and waiting alongside collet 532, notaligned with gripping device 530. Collets 532 and 534 may be any desiredcomponent holding devices, and preferably in this instance are colletsdesigned and shaped to hold an armature, such as shown in Lombardi U.S.Pat. No. 5,178,428. In the particularly preferred embodiment shown inthe drawings collets 532 and 534 grip the shafts of armatures 520 remotefrom the commutator end 522 of the armatures. This is done so that thecommutator end of the armature can be inserted in winding machine 500(and fusing machine 570 if a fusing machine is included as shown in FIG.5).

Collets 532 and 534 preferably are positioned on carriage 536, which isslidable on base 538 along tracks 540 and 542 (in directions 544 and546, parallel to the transverse axis of base 538). Base 538 (andtherefore everything mounted on base 538) is rotatable about verticalaxis 564. The alignment area of load/unload device 322 is determinedwith respect to base 538. Sliding of carriage 536 is actuated bypneumatic cylinder 548. It will be appreciated that collets 532 and 534may be directly slidably mounted on base 538 instead. Once collet 532receives a component to be processed, in this case an unwound armature,carriage 536 slides in direction 544 to align collet 534, carrying awound armature, with gripper 530. Thus collet 532 moves away from thealignment area of load/unload device 322 and collet 534 moves into thealignment area. Collet 534 transfers the wound armature to gripper 530,which rotates 180° about its vertical axis and descends to place thearmature on the pallet below the gripper. It will be understood that acomponent may be transferred between pallet 320 and one of collets 532and 534 without the use of gripping device 530 or by means other thangripping device 530. For example, an armature lifting device could comeup below armature 520 through the central aperture in pallet 320 toraise the armature off the pallet. (See, for example, Santandrea et al.U.S. Pat. Nos. 5,060,781 and 5,115,901 for discussions of this type ofapparatus and suitable pallets.)

In order to transfer armatures between collets 532 and 534 and gripper530, each collet slides along its longitudinal axis to approach andwithdraw from gripper 530. Collets 532 and 534 are respectively mountedon collet carriages 550 and 552, which respectively slide along slides554 and 556, parallel to the longitudinal axes of collets 532 and 534. Apneumatic cylinder, such as cylinder 558, actuates translation of eachcollet carriage along the longitudinal axis of the collet as desired. Itwill be understood that any other means for translating collets 532 and534 may be used. Preferably each collet has a rest position at which therear end of the collet (the end opposite the gripping portion of thecollet) is positioned at the end of its respective track and thegripping portion of the collet is positioned substantially completelyabove carriage 536. Thus, to approach gripper 530 (when base 538 isrotated about axis 564 so that the gripping portion of the collet isfacing gripper 530), a collet moves in direction 560. To return to itsrest position, the collet moves in direction 562.

Once a wound armature (or other processed component) is removed fromcollet 534, carriage 552 returns collet 534 to its rest position (collet532 should already be in its rest position) and base 538 is rotated 180°about the central axis 564 of load/unload device 322 (see also FIG. 7for this condition of the load/unload device). Central axis 564 remainsat a fixed location. Preferably, when rotation occurs, both collets arein their rest positions. A motor, reduction gear, and gear mechanism, orany other desired mechanism, such as intermittors, can be used to rotatebase 538. It will be understood that winder 500 need not be directlyopposite main conveyor 310, and therefore base 538 may be rotatedgreater or less than 180° about axis 564. Carriage 536 maintains itsposition relative to base 538 during rotation. Thus, collet 534, whichis now empty, is now aligned with winder 500.

Collet carriage 552 advances collet 534 in direction 562 toward winder500 to remove a wound armature from winder collet 566, and then returnscollet 534, along direction 560, to its rest position. If desired, agripper such as gripper 530 may be used to transfer the wound armaturefrom winder collet 566 to collet 534. Carriage 536 then translates alongdirection 544 to align collet 532, carrying an unwound armature (orother unprocessed component), with winder 500. Collet carriage 550advances collet 532 in direction 562 toward winder 500 to deliver thearmature for winding, and then returns collet 532, along direction 560,to its rest position. Once again, if desired, a gripper such as gripper530 may be used to transfer the unwound armature from collet 532 towinder collet 566. Base 538 then rotates 180° along central axis 564 tohave the gripping portions of collets 532 and 534 once again facegripper 530 so that the cycle can be repeated. Alternatively, base 538can rotate 90° to have the gripping portions of collets 532 and 534 faceanother processing machine such as fusing machine 570, and a similarexchange of processed components for components to be processed occursbefore returning base 538 to its initial position with the alignmentarea adjacent main conveyor line 310. (Fusing machine 570 may be aconventional device for producing finished mechanical and electricalconnections between the leads of the coils wound on the armature bywinder 500 and the commutator segments to which those coil leadsextend.) Preferably, when rotation of base 538 occurs, both collets arein their rest positions.

Schematic plan views of conveying system 300, showing the steps involvedin loading and unloading load/unload device 322, are illustrated inFIGS. 6 and 7. In FIG. 6, collet 532 is shown aligned with an unwoundarmature 600 (any other component to be processed may be used) carriedby pallet 320, i.e., collet 532 is shown at the alignment area ofload/unload device 322. Armature 600 is halted on main conveyor 310awaiting transfer (such as by means of gripper 530) to load/unloaddevice 322. If gripper 530 is used, gripper 530 lifts unwound armature600 from pallet 320 and rotates it 180° as described above. Collet 532advances in direction 560 toward gripper 530 to receive unwound armature600, and then retreats in direction 562 to its rest position.

Carriage 536 then translates in direction 544 along the width of base538 to position 536' to align collet 534 with gripper 530. Collet 534 isthereby placed at the same location at which collet 532 is shown in FIG.6, i.e., the alignment area, and collet 532 is thereby placed at colletposition 532'. Collet 534, carrying wound armature 610, advances indirection 560 to unload wound armature 610 to gripper 530, and thenretreats in direction 562 to its rest position. Gripper 530 rotates 180°as described above and lowers wound armature 610 onto the waiting palletwhich has just been unloaded and is stationary on main conveyor 310.These steps are skipped, however, if a wound armature has not yet beenloaded onto collet 534.

Load/unload device 322 is then ready to unload/load components to andfrom winder 500. Base 538 therefore rotates in direction 620 around itscentral axis 564 to present the gripping portions of collets 532 and 534to winder 500, as shown in FIG. 7.

After rotation of base 538, empty collet 534 is initially aligned withwinder collet 566 to receive wound armature 700, i.e., collet 534 is atthe alignment area, as shown in FIG. 7. Collet 534 advances in direction562 toward winder 500, receives wound armature 700, and retreats indirection 560 to its rest position on carriage 536. This step isskipped, however, if winder 500 has not yet begun winding armatures.Carriage 536 then translates in direction 544 to position 536' to aligncollet 532, carrying unwound armature 600 (see FIG. 6), with windercollet 566. Collet 532 is thereby placed at the same location at whichcollet 534 is shown in FIG. 7, i.e., at the alignment area, leavingcollet 534 at collet position 534'. Collet 532 advances in direction 562toward winder 500, unloads unwound armature 600 for winding by winder500, and retreats in direction 560 to its rest position on carriage 536.Base 538 is then ready to rotate in direction 720 around its centralaxis 564 to return the system to the condition shown in FIG. 6.

Pallet 320, from which an unwound armature was removed and on which awound armature has been loaded, is allowed to move along main conveyor310 as soon as the pallet receives the wound armature (i.e., before therotation 620 described above in connection with FIG. 6). Any palletsthat were queued up behind the pallet that was just unloaded and loadedcan also continue to move along conveyor 310.

The pallets on main conveyor 310 are halted by movable stop 342 only forthe time required by load/unload device 322 and gripper 530 toaccomplish the above-described operations of removing a component to beprocessed from the pallet and delivering to the same pallet a processedcomponent. Halting of the pallet occurs only if the load/unload deviceis ready to deliver a processed component (or if the processing machineis just starting up and needs an unprocessed component to work on). Thepallet immediately behind the stopped pallet will be halted when itcomes into abutment with the pallet stationary under gripper 530. Otherpallets will be stopped in succession by abutting against each other.

A computer or any other equivalent device can be used to monitor thestatus of the components in machine 332 and associated load/unloaddevice 322 to determine whether a pallet should stop at load/unloaddevice 322. If the load/unload device contains no processed componentand the processing machine is not in need of an unprocessed componentfrom conveyor 310, the pallet passes load/unload device 322 withoutstopping so that the pallet can reach the next load/unload device 324and processing machine 334. The pallet continues until a processingmachine has a load/unload device containing a processed component thatit needs to release (or until a processing machine needs an unprocessedcomponent from conveyor 310 in order to start up). At the end of mainconveyor 310, any pallets carrying components that have not yet beenprocessed can be returned by return conveyor 312 to the beginning ofmain conveyor 310 to attempt, another time, to find a free machine forprocessing.

Conveying system 300, operating as described above, typically requires apallet to remain stationary for a shorter time than the prior artsystems. Additionally, load/unload devices 322, 324, 326 are configuredand perform in a way that also requires less time than the load/unloaddevices of the prior art. It should also be noted that the time requiredto load and unload a processing machine is extremely short and that, asa consequence, the processing machines remain stationary withoutproducing for an extremely short time. A pallet only has to remainstationary long enough for an unprocessed component to be removed fromthe pallet and for a processed component (which was previously retrievedfrom the processing machine and which is therefore waiting in theload/unload device) to be loaded on the pallet. Similarly, a processingmachine only has to be stopped long enough for a processed component tobe removed from the processing machine and for an unprocessed component(which was previously retrieved from a pallet and which is thereforewaiting in the load/unload device) to be loaded in the processingmachine.

Preferably the systems of this invention are controlled so thatcompletion of a processing operation by a processing machine isanticipated by having the associated load/unload device perform anunload and load operation on a pallet and rotate about axis 564 beforethe processing machine completes its operation and therefore requiresthe next unprocessed component. The pallet just unloaded and loaded canimmediately resume its travel along conveyor 310. When the processingmachine completes its operation, the load/Unload device is immediatelyready to unload that machine and to load it with the unprocessedcomponent previously unloaded from a pallet. The processing machine canthen resume processing, while the load/unload device rotates back towardconveyor 310 to await a suitable opportunity to exchange thejust-received processed component for an unprocessed component onanother pallet. The pallets do not have to wait for any processingmachine operations or even for all load/unload device operations. Nordoes a processing machine have to wait for any pallet operations or evenfor all load/unload device operations. All significant waiting is doneby the load/unload device itself, which alternately holds an unprocessedcomponent waiting for a suitable time to transfer that component to aprocessing machine or holds a processed component waiting for a suitabletime to transfer that component to a pallet. These features make itpossible for the systems of this invention to achieve production ratesequal or comparable to those of FIG. 1 type systems having the samenumber of processing machines without the need for the more elaborateconveyor systems employed in FIG. 1 type systems,

System control of a production line operating in accordance with theprinciples of the present invention functions smoothly, efficiently, andproperly without requiring coding devices that need to be coded andread. This is possible because, contrary to the prior art systems (suchas the system of FIG. 1), there is no casual departure or return ofpallets from and to the conveyor of the present invention. Once palletsstart down conveyor 310 in a predetermined order, they remain in thatorder at least to the end of conveyor section 310. Thus, it is easier toidentify pallets and to know whether or not the pallet carries acomponent that needs to be processed. For example, a simple countingmeans can be used to count the advancement of the conveyor and thereforeof each pallet.

As mentioned above in connection with FIG. 5, another type of processingmachine such as fuser 570 can be added to the apparatus served by aload/unload device of this invention. If this is done, the load/unloaddevice preferably exchanges components with a pallet while processingmachines 500 and 570 are both operating, respectively, on two othercomponents. The load/unload device rotates toward processing machine 500and waits for that machine to complete its component processingoperations. The load/unload device then exchanges components withprocessing machine 500 and rotates toward processing machine 570.Processing machine 500 can immediately resume processing operations. Theload/unload device waits for processing machine 570 to finish itsprocessing operations and then exchanges components with that machine.Processing machine 570 can then immediately resume its processingoperations, while the load/unload device rotates toward conveyor 310 toawait an opportunity to exchange components with another pallet. In thisway a load/unload device of this invention can serve two or moredifferent processing machines performing sequential operations on acomponent.

It will be understood that the foregoing is merely illustrative of theprinciples of the invention, and that various modifications can be madeby those skilled in the art without departing from the scope and spiritof the invention. For example, any desired components other thanarmatures can be processed according to the method of the presentinvention. Additionally, equipment equivalent to the equipment shown canbe used to accomplish the method of the present invention. The describedembodiments are presented for the purpose of illustration rather thanlimitation, and the present invention is limited only be the claimswhich follow.

What is claimed is:
 1. Apparatus for conveying dynamo-electric machinecomponents having a magnetic core through at least a portion of aproduction line which includes a plurality of processing machines foroperating on said components, said apparatus comprising:a main conveyoralong which said components are conveyed on pallets past said processingmachines without possibility of transfer to an additional conveyortraveling in the same direction as said main conveyor; a stop forselectively stopping a pallet at a predetermined location along saidmain conveyor; and a load/unload mechanism for removing a component froma pallet stopped at said stop and placing a different component on thestopped pallet, said load/unload mechanism including two componentholders and first means for successively positioning each of saidcomponent holders relative to said stopped pallet so that a first ofsaid component holders can receive the component from said stoppedpallet and so that a second of said component holders can thereafterdischarge said different component for placement on said stopped pallet,wherein said main conveyor conveys said pellets one after another in apredetermined order past said plurality of processing machines, eachpallet passing one after another of said processing machines as saidpallet travels along said conveyor, said apparatus maintaining saidpredetermined order of said pallets as said pallets pass said pluralityof processing machines.
 2. The apparatus defined in claim 1 wherein oneof said processing machines is disposed adjacent said load/unloadmechanism, and wherein said load/unload mechanism further includessecond means for alternately positioning said component holders forexchanging components with a pallet on said main conveyor and forexchanging components with said one of said processing machines.
 3. Theapparatus defined in claim 2 wherein, when said second means positionssaid component holders for exchanging components with said one of saidprocessing machines, said first means is operable to successivelyposition each of said component holders relative to said processingmachine so that said second component holder can receive a componentfrom said processing machine and so that said first component holder canthereafter discharge another component to said processing machine. 4.Apparatus for conveying dynamo-electric machine components having amagnetic core through a production line which includes a plurality ofprocessing machines for operating on said components, said apparatuscomprising:a conveyor along which said components are conveyed onpallets; a stop for selectively stopping a pallet at a predeterminedlocation along said conveyor; and a load/unload mechanism for removing acomponent from a pallet stopped at said stop and placing a differentcomponent on the stopped pallet, said load/unload mechanism includingtwo component holders and first means for successively positioning eachof said component holders relative to said stopped pallet so that afirst of said component holders can receive the component from saidstopped pallet and so that a second of said component holders canthereafter discharge said different component for placement on saidstopped pallet, wherein said second component holder is already holdingsaid different component when said first component holder receives saidcomponent from said stopped pallet.